For example, bipolar plates are known for the electrical, thermal and mechanical connection of fuel cells, whereby these bipolar plates are fashioned continuous, i.e. without holes or clearances, so that a reaction medium that flows along the active surface of a bipolar plate can be located either above or below this plate according to the Prior Art. All other known intermediate elements that are not bipolar plates respectively use only one surface for the contact with the medium.
The continuous fashioning of the bipolar plates also has the disadvantage that the cooling or reaction medium is conducted over the active surface in a flow without an exchange of the medium occurring from the middle of the flow to the outer region of the flow. When the medium at the outside of the flow has been used, it cannot be replaced by unused reaction agent proceeding from the middle of the flow but must be replaced by new agent located at the outside of the flow, so that, to be brief, a high flow velocity of agent is required given optimally small agent flow diameters. It is thereby disadvantageous that, even given small agent flow diameters, the part of the agent that is in the middle of the flow always flows through the system unused.
Finally, the known bipolar plates or intermediate elements exhibit the disadvantage that the pressure transmission occurs non-uniform, namely with peak loads at the highest elevations of the bipolar plates.
The known bipolar plates and/or intermediate elements thus not only lack a possibility of effecting an exchange of the agent from the middle of the agent flow toward the outside of the flow within the agent flow on their active surface, a possibility of using the surface present at both sides (and, for example, effective in the cooling system) for contacting with agent but also lack the capability of forwarding mechanical pressure as uniformly as possible across their entire surface.
There is thus a need for bipolar plates that, just like the known bipolar plates, can be utilized as electrically, mechanically and thermally connecting intermediate elements in fuel cell stacks and that simultaneously reduce or entirely eliminate the aforementioned disadvantages.